Some words about noise and crosstalk which may be puzzling on V281.
As there are 4 amps inside V281 for balanced operation the noise figure suffers by 6 dB.
This is normal !!
Because on the other hand this amp is twice as powerful and you may reduce the volume by 6 dB to have the same volume like a SE amp.
Take a look at the dynamic range (129 dB) which is exactly the same on all amps.
The push-pull amp architecture of V281 is also responsible for the doubled output impedance compared to V220.
Double as much amps = twice output impedance.
Always keep in mind that inside V281 there are two SE amps with the technical data of V220 !
About crosstalk: everything lower than -80 dB is more than any source can deliver !!
Theoretically it is possible to upgrade the V220 to V281.
Take a look at the inside pictures somewhere here in the post.
The upper amp PCB, a different font panel PCB, the 4-pin socket and a couple of cables are making the difference.